Air drying unit



Oct. 23, 1951 c. c. CARSON AIR DRYING UNIT Filed Dec. 2, 1946 5 Sheets-Sheet l FIG. 2

FIG. 1

CLIFFORD C. CARSON flr/tozman Oct. 23, 1951 c. c. CARSON AIR DRYING UNIT 5 Sheets-Sheet 2 Filed Dec. 2, 1946 gwum'vtob CL/FFORD C. CARSON NMT C. C. CARSON AIR DRYING UNIT Oct. 23, 1951 5 Sheets-Sheet 3 Filed Dec. 2, 1946 C. C. CARSON AIR DRYING UNIT Oct. 23, 1951 5 Sheets-Sheet 4 Filed Dec. 2, 1946 FIG. 6

/E| CONTROL PANELE FIG. 5

Emma tom- CLIFFORD C. CARSON 0a. 23, 1951 C, c nsN 2,572,009

AIR DRYING UNIT Filed Dec. 2, 1946- 5 Sheets-Sheet 5 I 4 1 1 I93 ,I

205 I FILTER c0125 303 250 Mini sw/TCH FAN I DnmvE 12$? 5m. 9s 1 I96 --\202 276 T 23 278 269 g SOLENOID [/87 265 4 267 L SOLE/100 I I 9 K234 L FA maven MAIN 3; 3 /L SWITCH A50 200 21 22s HUI/p194 PM ""zlr I I88 LINES 3| POLE if? DAMPER LIMIT swncl-l 266 2i JWITCH HEAT/N6 C0! 2 I6 it, f2 2 240 LIMITSWITCH L, y 25 7 /e4 LN 262 -J 2 4 4 24? I qr 1 l THERMOSTAT 244 5 v #270 @455 2I8Q H AFETY Y I THERMOSTAT JUL xfg g' Hume/STAT TRANSFORMER WEQJ "l \280 LOUVRE DAMPER FIG. 7 CONTROL. UR

CLIFFORD c. CARSON Patented Oct. 23, 1951 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This application is a continuation-in-part of application Serial No. 552,856, now abandoned, filed September 6, 1944, for Air Drying Unit.

This invention pertains to apparatus for use in the conditioning of air and more especially to improvements in dehumidifying apparatus.

During peace time, there will be of necessity, a large number of decommissioned ships tied up at various navy yards. It is desirable, however, to maintain these ships in a substantially ready condition so thatthey can put to sea in a very short time and to make this possible, the greatest part of the equipment for these ships must be left on board.

It is an object of the present invention to provide apparatus for controlling the moisture-content of the air in the various compartments of ships, which may readily be installed, which will be automatic in operation and which will be rugged and require little or no care in operation or upkeep.

To this end and in accordance with one feature of the invention air to be dehumidified is passed through a bed of desiccant material such as silica gel where the moisture in the air is adsorbed. The desiccant material in absorbing the moisture increases in weight. A weight responsive device is provided which is actuated when the weight of the silica gel indicates that it is in a near saturated condition. The weight responsive device upon being actuated causes other apparatus to be rendered operative to evaporate the moisture from the desiccant by passing preheated air through the desiccant material to evaporate the moisture therein.

It is a characteristic of chemical type of desiccants, such as silica gel and activated alumina, that the vapor pressure of the moisture adsorbed in the desiccant tends to reach equilibrium with the vapor pressure of the air passing through it which is to be dehumidified. It is apparent to those skilled in the art that with air entering the drying unit at a low temperature prevailing in winter the desiccant will absorb a greater amount by weight of water vapor than in the case of warm weather. That is to say, the weight of the water which can be adsorbed by a particular desiccant varies with the temperature of the air passing through it.

Another feature of the invention makes use of a novel means of automatically compensating for this varying weight of adsorbed water in order that the machine will be switched to the reactivation portion of the cycle only after the bed of desiccant has adsorbed all of the water vapor that it is capable of adsorbing at the prevailing dry bulb temperature of the air handled. A further object of the invention is to provide for automatically compensating for the change in percentage of reactivation due to the change in temperature of the gas available for such reactivation. The amount of residual moisture remaining in a desiccant of the dry type is inversely proportional to the temperature at which reactivation is accomplished.

Another property of certain desiccants is that the adsorbing ability is increased by reactivating at a high temperature as compared to a low temperature. Thus it is seen that the ideal temperature of reactivation will be a temperature just below that temperature at which the desiccant material might be damaged by the heat.

In the apparatus illustrated this object is accomplished by automatically varying the amount of air passed through the desiccant bed, a constant rate of heat being supplied to the air stream, such amount of air flow being controlled as a function of the temperature of air leaving the desiccant bed. So long as the air is removing water from the desiccant the temperature of the bed will be lower than the temperature of the air entering the bed. As the reactivation nears completion the temperature drop through the bed decreases until finally when reactivation is completed there is no change in temperature of the air passing through the desiccant. When reactivating gas is at a low temperature the amount of such gas flowing would be decreased by closing dampers in the outlet to weather, such damper position being governed by a thermostat located in the stream of gas leaving the desiccant. When the gas for reactivation enters at a higher temperature, the heating unit would allow too great an increase hence gas entering desiccant would be too hot. The dampers would then automatically open to increase the flow of gas and decrease the temperature of gas passing through the bed. A proper setting of the thermostat would, therefore, allow reactivation to occur at a desirable temperature, regardless of the initial temperature of the gas available for reactivation.

The specific construction and operation of my device will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a perspective outside view of a device according to this invention.

Fig. 2 is a section on the line 22 of Fig. 8;

Fig. 3 is a sectional view on line 3-3 of Fig. 4;

Fig. 4 is a section on the line l4 of Fig. 3, some details being omitted for clarity;

Fig. 5 is a top plan view of a device according to this invention with cover removed.

Fig. 6 is a diagrammatic View on line i36 of Fig. 5; and

Fig. 7 illustrates the electrical control circuits of the machine.

The invention illustrated herein comprises in general, a drying unit it and an air pump '12 adapted to circulate air from an enclosed space which is to be treated through the drying unit until the latter, which is of the adsorptive type becomes saturated with moisture whereupon the circulation of the air being treated is discontinued, and a stream of heated atmospheric air is circulated by the air pump t2 through the drying unit. The air for regeneration of the unit is heated up by a heating coil l4 and a heat exchange unit iii. The change over from the .air being treated during the adsorption cycle to the atmospheric air for regenerating the drying unit is provided for by dampers i8 and 28 which are controlled by an electric circuit indicated generally at 2 I. I

The aforesaid elements are arranged in working relation to each other in housing 22 (Fig. l.) which consists of parallel walls 24, joined at one end by a circular end wall 26, and at the opposite end by a fiat end wall 28. The housing is completed by top and bottom walls 39 and 32 (Fig. 2). The lower portion of the housing is supported by two Z-bar supports 3 3 to afford clearance at the base of the unit so that it may readily be passed through the standard door on shipboard (Figs '1, 2 and 4).

The dimensions of the housing 22, as described, are such as to permit its passage through a standard door on any one of our fighting ships. .As shown in Fig. 3 an inner wall 36 is formed at the rounded end of the unit and part way along the parallel walls 2 the wall 35 extending from the bottom nearly to the top of the housing .22, and insulating material 38 is disposed between these walls so that the drying unit I is surrounded on three sides by insidat'ion. Spaced transverse insulating walls 48 and '42 are placed widthwise of the unit between the drying unit I 8 and the air pump l2, the wall 42 forming with the circular end wall 25 an enclosure within which the drying unit is disposed. The space between the walls 46 and 42, as shown in Figs. 3 and 4, constitute a passage through which air from the air pump [2 passes on its way to the drying unit ID- The heat exchange unit 16 is disposed in this passage between the walls 40 and 42. drying unit it is also insulated .as shown at 44 and a horizontal insulating wall 46 is disposed above the drying unit below the top 30 as illustrated in Fig. 4 to bridge the upper ends of the double walls, and hence to form a substantially closed insulated chamber.

The drying unit itself which is generally indicat-ed by the reference character l0, comprises a pair of concentrically arranged cylindrical foraminous screens '48 and 58, the latter being smaller in diameter than the former so that there is between the walls of the cylinders, an annular space 49. In this annular space 49 there are disposed a plurality of tubes 52. The foraminous cylinders 43 and are held in spaced relation 'to each other between a pair of end plates 54 and 56 by the tubes 52. As shown herein, this is accomplished by forming openings 58 in the end plates 54 and 56 through which the opposite ends of the tubes 52 are passed and which The bottom of the housing below the are fastened to these end plates at one end by welding or crimping and at the other end by nuts 59 threaded on the ends of the tubes. The upper ends of the cylinders 48 and 50 terminate short of the ends of the tubes 52 and between the upper ends of the cylinders 48 and 50 and the plate 56 there is disposed an outer frustm conical member 60, the lower end 82 of which sets into the upper end of the outer cylinder 48 and an inner frusto-conical member 64 the lower end 55 of which sets over the upper end of th inner cylinder 5!].

The aforesaid construction provides an annular trough-shaped space 68 at the upper end of the annular space'49 formed between the cylinder 48 and .59 for a purpose which will appear hereinafter. The frusto-conical member 60 is welded at its upper edge to the plate 56 and a central opening is formed in the plate 56 through which the upper end 6'! of the frusto-conical member 64 extends. The lower ends of the cylinders 48 and 59 are held in position by an annular flange 10 welded to the plate 54 and an upturned flange I2 which is formed around the periphery of an aperture E4, the latter being formed in the plate 54 for a purpose which will appear hereinafter.-

The material 5! for removing the moisture from the air which will be referred to hereinafter as the desiccant material, is a silica gel or any other suitable desiccant material disposed in the annular space 49 between the cylinders 48 and 50 and during the adsorption cycle it removes water vapor from the air being treated. The physical process which takes place durin the adsorption of the moisture changes considerable latent heat into sensible heat. In order that some of this sensible heat may be removed} part of the air passing through the drying unit is bypassed through the tubes '52 .and heat transferring fins It are provided :on the outer surface of the tubes 52 to more readily transfer the heat collected in the body of the desiccant material to the stream of airpassing through the tubes 52.

The air to be treated is conducted to the lower end of the unit and passes upwardly through the opening 74 in the lower wall '54, the inner cylinder 50, through the annular space "d9 which holds the desiccant material and out through the cylinder 48 to the annular space '47 surrounding the unit :and between it and the wall of the housing. To prevent the passage of the air into the space 4'! from below the unit before it goes through the bed of desiccant material, the bottom end plate 54 has at its peripheral edge, a reverse 'U-shaped annular wall '58 which cooperates with a vertical annular wall 89 fastened at its lower edge to the inner wall of the housing surrounding the drying unit in such 'a manner that the drying unit may have vertical movement "and yet the annular space All is sealed from the space below the plate 54.

In a like manner, the annular space at the upper end of the drying unit is sealed from the remainder of the housing by a transverse plate 86 fastened at 84 to a neck 82, the latter being welded at 66 to the end 61 of the frusto-conical member 54. The plate 86 is provided with U-shaped walls 88 at its peripheral edge which cooperate with the annular depending wall 90 .fastened to the inner wall of the housing. The

unit is suspended, for a purpose which .Will subsequently appear, for vertical movement "within the housing at the end of a link H38 which is pivotally fastened at I02 to one end of the neck 82 and at [04 to a horizontal arm I06. To seal 5 the upper end of the unit around the link I there is provided a bellows I08 one end of which is clamped between a pair of collars I I0 mounted on the link I00, and the other end of which is clamped against the upper wall 46 of the unit by a collar H2.

The air pump I2, is a size AJA-A standard navy type axial fan and will be hereinafter referred to as a fan, consists of a motor I09 and an impeller blade III arranged in a vertical position in a tubular housing H3, Figs. 2 and 4, which has a bell mouth inlet H6 at its lower end and a conical discharge tube H8 at its opposite end, the fan housing H3 and fan l2 being supported in the housing 22 bv a transverse partition H5 to which it may be bolted or welded. Connected to the conical discharge tube H8 is a vertical conduit portion I 20 having a horizontal portion I22 and a vertical portion I24 extending between the walls 40 and 42 which leads the air discharge from the fan I2 to a space I26 beneath the drying unit I0, that is, below the plate 54. In the conduit, at the bends therein, are turning vanes I28 which smooth out the flow of air as it passes around the bends in the conduit thereby preventing turbulence. The air in its passage through the conduit portion I24 also passes through the heat exchange unit I6 which as will appear hereinafter is inoperative during the adsorption cycle.

The present unit is so constructed that it can be used either by setting it into the compartment in which there is the air to be treated or by placing it outside of the compartment and connecting it to the compartment by conduits. To this end there is formed in the back wall of the housing 22 an inlet opening I 30 and an outlet opening I32, Fig. 3. If the unit is merely placed in the compartment and the compartment is then closed, the air in the compartment may be subjected to dehumidification by placing the apparatus into operation whereuponthe air pump I2 will draw the air to be treated into the opening I30 and discharge it through the opening I32. If, however, the apparatus is set outside of the compartment, the openings I30 and I32 may be connected to openings formed in the compartment by means of ducts I34 and I36.

After the unit has been operating on the adsorption cycle, and provided a humidostat which is associated with the apparatus, as will appear hereinafter, continues to call for dehumidification, the desiccant material ultimately becomes saturated with moisture. This will increase the weight of the drying unit I6 and cause it to tip the arm I 06 about a pivot I38, Figs. 4 and 6, which will in turn raise a rod I40, Figs. 4 and 6, connected to the arm I06'so as to trip a limit switch I86, Figs. 6 and 7, which will initiate the regenerative cycle.

During the regenerative cycle, the desiccant material .5I is dried out by the passage of heated air through the desiccant material 5|. To this end and in response to the operation of the aforesaid limit switch I86, the dampers I8 and 20 are caused to close the openings I30 and I32 and to uncover an opening I42 formed in the end wall 28 of the housing 22 through which air is sucked by the air pump I2 and is conveyed through the conduit portions I20, I22 and I24 to the compartment I26 below the drying unit I0 where it passes upwardly to the inside of the cylinder 50 in contact with the heating coil I4. The dampers I8 and 20 are actuated by a damper motor 200, Figs. 5 and '7, the operation of which will 6 appear hereinafter. To this end U-shaped arms I! and I9 are fastened at one end to the dampers I8 and 20 and are connected at their opposite ends to a link 23, the latter being adapted to be reciprocated by the motor 200 to pivot the U-shaped arms I! and I9 about their bights I21 in one direction or the other to swing the damper from a position covering the openings I30 and I32 to a position covering the openings I42 and I50 or vice versa.

After being heated, the air passes through the annular wall of the desiccant material 5| into the space 4! and from thence through the opening I50, which is uncovered by the damper I8 at the same time that the damper 20 uncovers the opening I 42, intoa conduit I44 which conducts it through the heat exchange unit I6 and discharges it through an opening I41 in one of the side walls. In order to prevent the heated air from being bypassed through the tubes 52 during the regenerative cycle, there is provided in the chamber space I26 below the plate 54 an annular sealing ring I46 with which the lower ends of the tubes 52 are adapted to be brought into contact by the downward movement of the drying.

unit I0 when it becomes loaded with moisture. This annular sealing ring I46 is supported in the chamber space I26 by a bracket I48 resting on the bottom wall 32 of the housing 22.

It has been determined by experiment that if the desiccant material 5| is regenerated at a fairly high temperature it will have better adsorption properties at low humidities than if it were regenerated at a low temperature. A temperature of about 350 F. is suitable and in order to maintain the bed of desiccant material 5I at this temperature and to keep it substantially uniform throughout the drying cycle, the volume of air passing through the desiccant material 5| during the regenerative cycle is governed by centrally pivoted multi-blade dampers I54 placed in the discharge opening I41 beyond the heat exchanger I6 as illustrated in Fig. 3, the dampers I54 in turn being controlled by a thermostat I52 disposed in the air stream just ahead of the heat exchanger I6 in the conduit I44, as shown in Fig. 3. The amount of opening or closing of the louvre damper I54 will be determined by the temperature of the air stream coming from the bed of desiccant material 5| through the opening I 50. The louvre dampers I54 are operated by a motor I55 and links |5I and I53, the motor being in the circuit containing the thermostat I52 and being connected in such a manner that it will operate in reverse directions to open or close the discharge opening I41.

The control mechanism I59 for operating the limit switch I86 which causes the unit to change from the adsorption cycle to the regenerative cycle, and vice versa, is shown in Fig. 6. Specifically, a horizontal arm I56 extends from the lower end of the rod I40 through vertical slots I69 in vertical walls I68 which are secured between upper and lower supporting brackets I6I and I63 mounted on a side wall 24 of the housing 22. Between these walls I68 are slidably disposed a pair of plates I 58 having knubs I 64 fixed thereto. Corresponding knubs I64 are fastened to the opposite sides of the arm I56. Between the opposite sides of the arm I56 and the parallel plates I58 there are disposed a pair of upper and lower springs I60 and I62, the springs being held in position by the knubs I64 on the arm I56 and on the plates I58.

The springs I60 and I62 tend to center the arm 7 I59 withrespect to the plates I58 and tc-counterbalance the weight of the drying unit I9. Between the'lower plate I59 and thelower brackets I63 there is disposed a bellows I12. 'Theupper bracket I6I 'has a screw I79 'adjustalo'ly threaded therethrough and presses against the upper movable plate I58. The screw I19 has a head I'I4 thereon to facilitate rotation thereof, and hence adjustment of the position of the upper plate I58, so that an initial balance may be obtained. The screw is adapted to be locked in any given position by a'lock nut I76.

The bellows H2 is hollow and 'is connected to a capillary tube I78 which passes through the lower bracket I53, the tube I18 being connected to :athermcstat H! which is disposed in the inlet duct I34. In the bellows I12 capillary tube I18 and thermostat I TI is a'volatile fluid which upon expansion will expand the bellows and hence compress the lower spring I92. The pressure of the bellows I72 compensates for difference in temperature, that is, at a high temperature during'warm weather the desiccant material will take up less moisture than at a lower temperature. Hence, to make the apparatus operate at optimum capacity it is desirable to cause it to remain in the adsorption stage until the desiccant .5] has adsorbed the maximum amount of moisture. This is accomplished by decreasing the tension in the lower spring H52 as "the ten perature decreases so that in cold'weather it will take 'a greater weight to overbalance the limit switch I86. 'Thls'is taken care of automatically by the bellows I12 which will apply toor remove pressure from the lower spring I92; thus-at high temperature, the lower spring l92 is compressed thereby causing it :to resist ovcrbalancing until the desiccant material 5| has taken up enough moisture to saturate it, whereas if thetemperature .is low, the pressure of the bellows H2 will be lessened against the lower spring .l62, thereby allowing the drying unit to adsorb a greater amount of moisture before it overbalances the upper spring I99. The arm I55 carries near its end a pin I89 which cooperates with a slot I84 formed .in the end of a lever I82 which upon movement will operate the limit switch indicated at I86.

The air being treated and also the air employed for regeneration of the desiccant material 5I carries dust, and to prevent clogging up the bed of desiccant material 5% which would render it ineffective, it is desirable to filter the air before it reaches the desiccant material 5|. To this end a filter I97, Fig. 3, is placed through access door I31 into a filter frame I39 across the openings I39 and I42 through which the 'air from either of these openings must pass. The filter core I91 may be removed from frame I39 through door I 31 when 'filled with dust and be replaced by a fresh filtercore. Toprevent the apparatus from being started while the core is not in position within the filter frame, a switch 299 which will be described hereinafter is placed in the filter frame I39 in a position to be opened by the removal of the filter core I91 thereby to break the circuit so that the apparatus will become inoperative. The condition of the filter core I91, that is the amount of dust that it contains, may be determined visibly by a draft gauge 8I connected to the opposite sides of the filter frame The electric circuit for operating the unit on its adsorption and regenerative cycles is controlled by the limit switch I96 as referred to above, and for convenience "in the description of the circuit, is shown in Fig. '7 diagrammatically. The circuit, which is as a whole designated by the reference character 2I, is supplied with power from power lines I88 by way of a main switch I99 and power conductors I92 and I93. Connected across the conductors I92 and I93 is the fan motor I99 which is provided with a fan starting switch I96. The heating coil I4 is also connected across the conductors I92 and I93 and have a heater starting switch I98. In the operation of the device as heretofore pointed out, the dampers I8 and 29 are operated to cut off the supply of air from the compartment being treated and to permit the introduction of atmospheric air "and these dampers are operated by a damper motor 299 which is connected across the conductors I92 and I93 by way of a damper motor starting switch 292.

During the adsorption cycle only the fan I2 is in operation, since during this period all that takes place is the recirculation of the air to be treated through the drying unit I9. The circuit permitting operation of the fan I2 during this period may be traced in Fig. 7 from the power conductor I92 through a conductor 294, the filter core switch 296, conductor 298, fan startin switch I 96, a conductor 2I9, bipcle switch terminals 2I2 and 2'I4, a-conductor 2I6, a humidostat 2i 8 in the space being treated, and termi nal 229 to the terminal 222 which is directly connected by the conductor 224 to the power conductor I93. It is to be observed that this circuit is normally closed through the filter core switch 296. The filter core switch 296 is held closed only so long as there is a filter core I9! in the filter frame I39, as previously described. If when this filter core is being replaced, some one attempts to start the machine, the filter core switch 295 will prevent operation thereof.

In this condition, that is during the adsorption cycle, the heat coil I4 is not in operation, and the damper motor 299 is inoperative. That these elements are not in operation will be seen by reference to these circuits. Referring to the circuit for the heat coil I4, it can be traced from the power conductor 192 by way of conductor 294, filter core switch 296, conductor 276, heater starting switch I98, conductor 279, safety thermostat I51, conductor 279, contacts 264 and 258, conductor 269 to terminal 228. Since the terminal 228 is not connected across the terminal 239 during the adsorption cycle, and the terminal 239, in turn is connected to the opposite one of the conductors I93 by the conductor 23I, the heater circuit is opened.

In like manner, beginning at one side of the conductor I92 and going by way of the conductor 294, filter core switch 296, conductor 298, conductor 259, damper motor starting switch 292, conductor 252, terminals 254 and 259, conductor 259 to terminals 232 and 234, during the adsorption cycle, this circuit is here broken and there is no connection between terminals 232 and 234 and the circuit can only be completed during the adsorption cycle through conductors 256 and 262 back to the'opposite power conductor I93.

When the desiccant material is completely saturated and the limit switch I86 is operated so as to initiate the regenerative cycle, the operation of the limit switch I86, as seen in Fig. 7, through conductors I8] and I89, closes. the contacts 244 and 246. The closing of the two .contacts .242 and .246 will energize solenoid 265 to cause a 'multi-pole switch 248 to move to its op- 9 posite position. When this happens, contacts 232 and 234 will be closed and contacts 236 and 238 will be broken. As a result, the damper motor circuit will be completed by way of the conductor 250, the damper motor starting switch 202 and the contacts 254 and 258, conductor 259 to operate the damper motor 200. After the damper motor has moved the damper to close the openings I30 and I32 the damper limit switch 260 will snap away from the contacts 254 and 258 and into contact with the contacts 240 and 242.

During the period when the damper motor 200 is moving the dampers I9 and 20 to the position covering the openings I30 and I32 from the position coverin the openings I42 and I50, it is desirable to discontinue the operation of the fan. This is accomplished in the circuit shown herein by movement of the multi-pole switch 248 which upon closing the contacts 232 and 234 causes a solenoid 261 to move a bi-pole switch 266 upwardly thereby to disconnect the terminals 2l2 and 2I4. This breaks the fan motor circuit. When the damper limit switch 260 has moved over to complete the circuit through the terminals 240 and 242, however, the fan motor circuit is again established to the bi-pole switch 266 causing it to reverse its position and hence to again complete the circuit through contacts 2l2 and 2M, so that the fan is again put in operation. In this position of the bi-pole switch 266 the heater I4 is also set in operation, as may be seen by reference to Fig. 7, its circuit being completed from the conductor I92 by way of the conductors 216, 218, the safety thermostat I5'I, conductor 210, the termina s 264 and 268, conductor 269 and the terminals 228 and 230 via conductor 23I to power conductor I93. A transformer 212 is connected in this heater circuit by way of conductors 210 and 274 for supplying power to a louvre damper control circuit 200. The circuit 280 is controlled by the thermostat I52 to operate the louvre damper, mo-

,tor I55 for changing the position of the louvre dampers I54 in accordance with the temperature prevailing at outlet I50. Sincev this circuit is conventional and does not present any novel subject matter, it will not be described further herein.

While the unit as thus far described and illustrated shows the drying unit in a vertical position, such construction is not necessary to the operation of the machine. The vertically disposed foraminous cylinders 48 and 50 may be disposed in a horizontal position or removable trays may be employed if this is found tobe convenient. In any construction employed, the units will be arranged to actuate the operating circuit in a manner similar to that described above.

Having described the construction of the apparatus in detail, the operation thereof will now be clear as set forth hereinafter. The apparatus having been placed in or adjacent to a compartment to be treated, and in the latter case connected to the compartment by the conduits I34 and I36, is started by closing the main switch I90. If the condition of the air in the compartment to be treated is such as to cause the humidos-tat 2I8 to call for operation of the drying unit I0, the operating circuit 2| will be closed and the fan I2 will immediately start and will suck air from the compartment being treated through the opening I30 into the intake side of the fan through the bell mouth H6 and will discharge it into the vertical conduit portion I20 where it will be conveyed by way of will be out of contact with the sealing ring I46 and hence part of the air sucked in by fan I2 will pass upwardly through the inside of the cylinder 50 and another part of the air will pass upwardly through the tubes 52. The air which passes upwardly to the inside of the cylinder 50 cannot pass through the upper end of the cylinder but must pass through the walls of the cylinder and the desiccant material 5I where it will give up its moisture to the desiccant material 5I.

The adsorption of the moisture is part of a physical action in which latent heat of the vapor is-changed to sensible heat, and this sensible heat is substantially absorbed by the air passing through the tubes 52, the fins I6 facilitatin such absorption. The air from the upper ends of the tubes 52 and the air which passes through the desiccant material 5| recombines and is discharged through the outlet I32 to the chamber being treated. When the bed of desiccant material 5I has become substantially saturated, the weight of the moisture and unit I0 is such as to overbalanc-e the action of the springs I60 and I62 and causes it to move downwardly until the lower ends of the tubes 52 rest on the sealing ring I46.

This downward movement of the drying unit I0 overcomes the toggle spring in limit switch I86 and actuates to the regenerative cycle. This causes the damper motor 200 to be put into operation, which in turn moves the dampers I8 and 20 to the position covering the opening I30 and I32 and uncovering the openings I42 and I50. During the movement of the dampers from one position to the other, the fan I2 is temporarily stopped as described previously. As soon as the openings I30 and I32 are closed, however, the circuit is so set up that the fan I2 is again put into operation and the heater I4 is energized. Air is then drawn in from the atmosphere or other source and is conducted to the chamber I26 where it passes upwardly through the inside of the cylinder 50 and is heated by the heater I4 prior to its passage through the body of the desiccant material 5 I.

Because the lower ends of the tubes 52 are closed all of the heated air passes through the body of desiccant material 5|. This air is discharged through the opening I50 and through the heat exchanger I6 which is adapted to transfer part of the heat to the incoming air to preheat it and hence to provide for more economical operation of the apparatus.

The temperature of the desiccant material 5I is maintained substantially uniform by the thermostat I52 which is placed adjacent to the opening 11 reaches a predetermined critical temperature which is approximately 500 F. in the case of silica gel. I

When suflicient heated air has been passed through the body of desiccant material 5| to evaporate substantially all the moisture therein, the weight of the drying unit In becomes less and the springs I60 and I62 overcomes the resistance of the toggle spring in the limit switch 86 and raise the drying unit ID by means of the above described linkage, and thus operates the limit switch I86 so that the adsorptioneycle is again brought into operation. The unit ID will automatically repeat the cycle of operation related above as long as the humidostat 2 l8 in the compartment being treated calls for such treatment and will then automatically stop.

While the unit has been described herein asuseful for conditioning the air in decommissioned ships to keep their contents in good condition, it is also within the scope of the invention to employ such units in merchant vessels to preserve goods and cargo in a satisfactory condition as the vessel passes from one climate to another. It is especially valuable where perishable cargo is being transported, such as fruits, etc. L

The invention described herein may be manufactured and used by or for the Government of the United States of America for overnmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In a machine for removing water vapor from air having an adsorbing cycle and a regenerative cycle, a bed of desiccant material comprising concentrically arranged foraminous hollow cylinders having an annular space between them in which there is disposed a desiccant material, a plurality of impervious tubes in the annular space arranged parallel to the axis of the cylinders, the ends of which tubes terminate at the opposite ends of the cylinders, means including conduits and a fan for circulating a stream of the air to be treated through the apparatus, means includin air passages connecting with said conduits for causing a portion of the air to pass through the annular wall of the desiccant material from the inner cylinder outwardly, and another part through the tubes to remove the heat added to said desiccant material by the dehumidifying action thereof, and motor operated valve means for closing the ends of the tubes during the regenerative cycle to cause all of the air circulated through the apparatus to pass through the desiccant material said valve means being operative in response to closing a circuit thereto as th desiccant material approaches saturation. V

2. In a machine for removing water vapor from air havin an adsorbing cycle and a regenerative cycle, a bed of desiccant material comprising a hollow cylindrical body of desiccant material, impervious tubes extending through said cylindrical body of desiccant material from end to end thereof parallel to the axis thereof, motor drivenfan means communicating with conduit means for creating a pressure difierential which results in the movement of the air to be treated radially through said wall and axially through the tubes to remove the heat added to said desiccant material by the dehumidifying action thereof, motor driven damper means for interrupting the passage of the air to be treated through the bed and tubes when said desiccant material is substantially saturated and for causing heated air to be introduced under pressure to the inside of said cylindrical body,

means responsive to substantial saturation of the desiccant material for operation of said damper means and linkage means connected operatively to the damper means simultaneously to close the ends of the tubes thereby to prevent the passage of the air axially through the body of desiccant material. I

3. In a drying apparatus, a bed of desiccant material, a fan having suction and discharge sides, a conduit connecting the discharge side to the bed of desiccant material, a heater between the bed of desiccant material and the discharge side of the fan, a conduit connected to the suction side of the fan having ports therein open to the fluid to be treated and to the atmosphere, a damper in the suction conduit operable to close one of said ports, and gravity operated switch and motor means operable by the loading of the desiccant material to cause the damper to close the port open to the fluid to be treated, to stop the fan during the movement of the damper and to render the fan and heater operative upon completion of the movement of the damper.

V 4. In a drying apparatus having an adsorbing cycle and a regenerative cycle, a bed of desiccant material a plurality of impervious tubes extending therethrough, a fan having suction and discharge sides, a conduit connecting the discharge side of the bed and tubes, a heater between the bed and discharge side of the fan, means rendering said heater inoperativeduring the adsorbing cycle, a conduit connected to the suction side of the fan having ports therein open to the fluid to be treated and to a drying fluid, a damper in the suction conduit operable to close one of said ports, switch means operable by the loading of the desiccant material, and motor driven linkage means controlled by said switch means to cause the damper to close the port open to the fluid to be treated, to close said tubes and to render the heater operative.

5. In a drying apparatus a body of desiccant material, means ra'r circulating air to be treated through the body of desiccant material to adsorb the moisture therein, means for counterbalancing the body of desiccant material comprising a pivoted lever, a link connecting said body of desiccant material to said lever, yieldable means secured to said pivoted lever counterbalancing said body of desiccant material, said yieldable means being adjustable to overbalance the weight of the body of desiccant material when same is substantially free of adsorbed moisture, and to be overbalanced by the weight of the body of desiccant material when same is substantially saturated, electroresponsive means including a circuit and switch operable by the movement of the body of desiccant material from unsaturated to saturated position for initiating a regenerative cycle and thermoeicpansive biasing means attached to the yieldable means and in the treated air stream for automatically varying the tension in the yieldable means in inverse ratio to the temperature of the air being treated and thereby decrease its yield point in proportion to the decrease in saturation weight as the temperature of the air being treated rises.

6. In a drying apparatus, a body of desiccant material, means for circulating air to be treated through the body ofdesiccant material to adsorb the moisture therein, means for counterbalancing the body of desiccant material comprising a pivoted lever, a link connecting said means secured to said pivoted lever counterbalancing said body of desiccant material, said yieldable means being adjustable to overbalance the weight of the body of desiccant material when same is substantially free of adsorbed moisture, and to be overbalanced by the weight of the body of desiccant material when same is substantially saturated, electroresponsive means including a circuit and a switch operable by the movement of the body of desiccant material from unsaturated to saturated position for initiating a regenerative cycle and thermoresponsive means attached to the yieldable means and in the treated air space to automatically vary the yield point in the yieldable counterbalancing means as a function of the adsorbing capacity of the body of desiccant material relative to the psychrometric condition of the air being treated.

'7. In a drying apparatus, a body of desiccant material, means for circulating air to be treated through the body of desiccant material to adsorb the moisture therein, means for counterbalancing the body of desiccant material comprising a pivoted lever, a link connecting said body of desiccant material to said lever, yieldable means comprising two springs oppositely disposed and tensioned and secured to said pivoted lever counterbalancing said body of desiccant material, said yieldable means being adjustable to overbalance the weight of the body of desiccant material when same is substantially free of adsorbed moisture, and to be overbalanced by the weight of the body of desiccant material when same is substantially saturated, means attached to the junction of said springs and operable by the movement of the body of desiccant material from unsaturated to saturated position for initiating a regenerative cycle, means for manually adjusting the tension of one of said springs, a bellows biasing the other of said springs, a bellows controlling thermostat, said thermostat being located in the air stream being treated before the air enters the desiccant bed, the load on said second spring being thereby automatically varied inversely with the temperature of the air being treated, thus compensating for the varying saturation point of adsorbed moisture in the desiccant bed as the temperature of air being treated changes.

8. In a drying apparatus, a body of desiccant material, means for circulating air to be treated through the body of desiccant material to adsorb the moisture therein, means for counterbalancing the body of desiccant material comprising a pivoted lever, a link connecting said body of desiccant material to said lever, yieldable means comprising two springs oppositely disposed and tensioned and secured to said pivoted lever counterbalancing said body of desiccant material, said yieldable means being adjustable to overbalance the weight of the body of desiccant material when same is substantially 60 free of adsorbed moisture and to be overbalanced by the weight of the body of desiccant material when same is substantially saturated, means attached to the junction of said springs and operable by the movement of the body of desiccant material from unsaturated to saturated position for initiating a regenerative cycle, means for manually adjusting the tension of one of said springs, a bellows biasing the other of said springs, a bellows controlling thermostat, a capillary tube connecting said thermostat to said bellows, said thermostat being located in the air stream being treated before the air enters the desiccant bed, the load on said second spring being thereby automatically varied inversely with the temperature of the air being treated, thus compensating for the varying saturation point of adsorbed moisture in the desiccant bed as the temperature of air being treated changes.

9. In a drying apparatus, a body of desiccant material, means for circulating gas to be treated through the body of desiccant material to adsorb the moisture therein, yieldable means counterbalancing the weight of the body of desiccant material, said yieldable means being adjustable to overbalance the weight of the body of desiccant material when same is substantially free of adsorbed moisture, and to be overbalanced by the weight of the body of desiccant material when same is substantially saturated, means operable by the movement of the body of desiccant material from unsaturated to saturated position for initiating a regenerative cycle, and means including a thermostat in the circulating gas to automatically vary the yield point in the yieldable counterbalancing means as a continuous function of the adsorbing capacity of the body of desiccant material relative to the psychrometric condition of the gas being treated.

CLIFFORD C. CARSON.

REFERENCES CITED The following references are of record in the file of this patent: 

